Coupling arrangement between an electron discharge device and cavity resonators



April 3, 1951 w. R. RAMBO 2 547 411 COUPLING ARRANGEMENT BETWEEN ANELECTRON DISCHARGE DEVICE AND CAVITY RESONATORS Filed Nov. 6, 1945 IFEEDBACK LOOP INVENTOR WILLIAM R. RAMBO ATTORNEY Patented Apr. 3, 1951COUPLING ARRANGEMENT BETWEEN AN ELECTRON DISCHARGE DEVICE AND CAVITYRESONATORS William R. Rambo, Cambridge, Mass assignor to the UnitedStates of America as represented by the Secretary of War ApplicationNovember 6, 145,'s'eria1No. 627,047

4 Claims. 1

This invention relates generally to electrical apparatus and moreparticularly to cavity type oscillators.

Oscillators which utilize tuned. lines or cavities have been extensivelyused and are well known to those experienced in the art. When cavitieshave been used, one method of obtaining feedback has been to cut holesin the walls of the cavities between which feedback is desired. Thismethod is unsatisfactory when it is desired to operate the oscillatorover a wide frequency range.

It is an object of this invention to provide a means for externalfeedback in a cavity type oscillator.

It is a further object of this invention to provide feedback means in acavity type oscillator which operates over a wide frequency range.

Other objects, features and advantage of this invention will suggestthemselves to those skilled in the art and will become apparent from thefollowing description of the invention taken in connection with theaccompanying drawing in which the single figure is a cross-sectionalview of a cavity type oscillator embodying the principles of thisinvention.

Referring now more particularly to the drawing, a cross section of thecoaxial cavity resonator and feedback system is shown. The innerconductor in of one coaxial cavity resonator in this instance isconnected to the cathode K of the oscillator tube. The tubing ii formsthe outer conductor of one coaxial cavity resonator and the innerconductor of the other cavity resonator and is larger in diameter thanthe grid ring i2 of the oscillator tube. The tubing l3 forms the outerconductor of the other coaxial cavity resonator and in this instance isconnected to the plate It of the oscillator tube. Glass envelopes areprovided forming an airtight space about the cathode K, grid G and plateP of the tube. The cathode heater and conventional lead-out connectionstherefrom are not shown.

The conductor ll extends beyond the usual point of contact with the gridand is then folded back, contacting the grid by means of fingers I6.Bald fingers are arranged concentrically around the grid ring.

Several of the grid contacting fingers I! are extended and formed intoan 8 shape as shown. The upper portion of the 8 passes through alongitudinal slot in the conductor ii and is connected to the conductorII at one end of the aforementioned slot, thus forming two loops, oneloop extending into one cavity resonator and the otherin the secondcavity resonator. The "grid contacting fingers iii are made of resilient'rn'ajterial so that they will be held against the grid ring of the tubeby spring action, thus assuring electric contact. The quantity of gridcontacting fingers which is formed into feedback loops is determined bythe amount of feedback required.

This method of feedback provides a low-reactance inductive couplingbetween the plate and grid circuits of the oscillator. The feed-backloop position is close to the grid plane of the oscillator tube bothphysically and electrically. Proper feedback is thus achieved over awide range of frequencies.

While there has been described what is at present considered to be thepreferred embodiment of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the scope of the invention.

What is claimed is:

1. An ultra high frequency arrangement comprising a tube having acathode, grid, and anode; inner, intermediate, and outer coaxialconductors forming a pair of coaxial cavity resonators, said inner andouter conductors being coupled to said cathode and said anoderespectively, said intermediate conductor being spaced from said grid;and a feedback loop connected between said intermediate conductor andsaid grid extending into the inner one of said coaxial resonators andarranged to extend into the outer one of said coaxial resonators throughan aperture in said intermediate conductor adjacent the connection tosaid grid.

2. An ultra high frequency arrangement comprising a tube having analigned cathode, grid, and anode, said grid having an extension aboutsaid cathode; inner, intermediate, and outer coaxial conductors forminga pair of coaxial cavity resonators, said inner and outer conductorsbeing coupled to said cathode and anode respectively, said intermediateconductor being spaced from said grid: and a. plurality of couplingmeans and anode, said grid having an extension about said cathode;inner, intermediate, and outer coaxial conductors forming a pair ofcoaxial cavity resonators, said inner and outer conductors being coupledto said cathode and anode respectively, said intermediate conductorbeing spaced from said grid; and an S-shaped feedback loop connected atone end to said intermediate conductor on the side of the inner one ofsaid coaxial resonators and at the other end to said intermediateconductor on the side of the outer one of said coaxial resonators, saidloop extending through an aperture in said intermediate conductoradjacent said grid and contacting said grid extension at a point remotefrom said grid.

4. An ultra high frequency arrangement comprising a vacuum tubeincluding a planar aligned cathode, grid, and anode, said grid includinga cylindrical extension about said cathode; three coaxial conductingcylinders arranged concentri- 2o cally, the inner and outer ones of saidcylinders being connected to said cathode and anode respectively, theintermediate one of said cylinders being terminated at a point adjacentto and spaced from said grid and including an aper ure substantially inthe plane of said grid; and resilient conductors connecting saidintermediate cylinder and points on said grid extension remote from saidgrid and extending into the space between said inner and intermediatecylinders, at least one of said conductors forming an S-shaped loopextending through said aperture into the space between said intermediateand outer cylinders and connected to said intermediate cylinder on theside facing said outer cylinder.

WILLIAM R. RAMBO.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PA'IEN'iIPS

